1. Field of the Disclosure
Embodiments disclosed herein relate generally to downhole drilling components. More particularly, embodiments disclosed relate to apparatus and methods to control fluid communication to bottom hole assemblies.
2. Background Art
In the drilling, completing, or reworking of oil wells, a variety of downhole tools may be used. FIG. 1 shows one example of a conventional drilling system for drilling an earth formation. The drilling system includes a drilling rig 10 used to turn a drilling tool assembly 12 which extends downward into a wellbore 14. Drilling tool assembly 12 includes a drillstring 16, a bottom hole assembly (“BRHA”) 18, and a drill bit 20, attached to the distal end of drillstring 16.
Drill string 16 may comprise several joints of drill pipe 16a connected end to end through tool joints 16b. Drillstring 16 may be connected, or “made-up”, where drill pipe 16a is tightened to a certain amount. Drillstring 16 maybe disconnected, or “broken-out”, where drill pipe 16a is loosened and taken apart. Drill string 16 transmits drilling fluid (through its central bore) and rotational torque from drill rig 10 to BHA 18. Drill pipe 16a provides a hydraulic passage through which drilling fluid is pumped. The drilling fluid discharges through selected-size orifices in the bit (e.g., “jets”) for the purposes of cooling the drill bit and lifting rock cuttings out of wellbore 14 as it is drilled.
Bottom hole assembly 18 includes a drill bit 20 and may also include additional components attached between drill string 16 and drill bit 20. Examples of additional BHA components include drill collars, stabilizers, measurement-while-drilling (“MWD”) tools, logging-while-drilling (“LWD”) tools, and downhole motors.
In some instances, well-intervention operations may be conducted using single-strand or multi-strand wireline or cable for intervention in oil or gas wells. Logging while drilling (LWD) is the measurement of formation properties during the excavation of the hole, or shortly thereafter, through the use of tools integrated into the bottom hole assembly. LWD, while sometimes risky and expensive, has the advantage of measuring properties of a formation before drilling fluids invade deeply. Further, many wellbores prove to be difficult or even impossible to measure with conventional wireline tools, especially highly deviated wells. In these situations, LWD measurement ensures that some measurement of the subsurface is captured in the event that wireline operations are not possible.
During downhole operations, for example, drilling, workover, and/or completion, one or more fluids may be present in both the bore of the drillstring and an annulus region formed between the drillstring and casing in the wellbore. When making up or breaking out connections in a wellbore having fluids present in the bore and the annulus region, unwanted fluid flow may occur in that the fluid from the annulus may rush into and up the bore of the drillstring. Such an occurrence is called a “U-tubing” effect and is well known in the industry. The U-tubing effect may be caused by a disturbance in the fluid equilibrium of the wellbore. For example, the fluids in the different volumes (i.e., the bore and the annulus region) may attempt to “level out,” thereby creating equilibrium in the wellbore. Making up and/or breaking out drillstring connections interrupts the equilibrium and causes the unwanted flow of fluid into the bore.
Accordingly, there exists a need for a device to control fluid flow through a drillstring bore during downhole operations such as when making up or breaking out connections. Also, a device through which wireline tools and cables may be run downhole with minimal restriction would be well received in industry.